The objectives of this proposed research are to determine the components of human enamel, saliva, or metabolic products of dental plaque bacteria that function in the binding of actinobolin to human enamel. Assuming a factor is found in enamel, dental plaque, or saliva that is involved in the binding of actinobolin to enamel, this factor will be characterized with respect to its inorganic nature, molecular weight, stability and reactivity. For this study a spectrophotometric assay will be used to measure the levels of actinobolin bound by hydroxylapatite and powdered human enamel, and to what extent do saliva, fluoride, etc., act in this binding. In additional work, chemical analogs of actinobolin will be used to determine what specific chemical modifications to the actinobolin molecule influence its binding to hydroxylapatite and human enamel.